105. Near-Death Experience Research Debate With Dr. Steven Novella

Yale University Neurologist skeptical of near-death experience research claims.

Join Skeptiko host Alex Tsakiris for the second in a two-part series with Yale University Neurologist, Dr. Steven Novella. During the hour-long interview Dr. Novella had this to say about the near-death experience research, “It’s descriptively very broad and it may have as many different causes as there are types of experiences that people describe, that are being lumped into this sort of broad category of experiences we’re calling near-death experiences.”

But, this view was immediately challenged by Skeptiko host Alex Tsakiris, “I don’t see where in the literature… particularly among near-death experience researchers, where there is this broad collection of different symptoms that are being lumped together, or experiences that are being lumped together. If anything, it seems like they’re honing in more and more…”

Novella and Tsakiris also discuss anesthesia awareness as a possible explanation for near-death experience accounts, ” Any anesthesiologist will tell you… that patients can wake up during anesthesia… that is a perfectly plausible explanation for those cases.”, Novella stated.

Tsakiris replied, “It doesn’t hold up… first of all its rare… the other thing is it has all sort of symptoms associated with it that don’t show up in any of these cases.

Alex Tsakiris: Today we welcome back to Skeptiko, Dr. Steven Novella, host of the very popular Skeptic’s Guide to the Universe show. Steve also runs the Neurological Blog, and makes frequent media appearances representing the skeptical community. Those are just his side interests. During the day, he’s a highly-regarded academic neurologist at Yale University School of Medicine. With that, Steve, welcome back and thank for joining me tonight.

Dr. Steven Novella: Hi, Alex. Thanks for having me back.

Alex Tsakiris: Steve, as you know, on the last podcast of Skeptiko, I responded to some statements you had made about near-death experience research. You were nice enough to come back on so we could sort through exactly where you’re coming from and how you view this phenomenon. That’s what I thought we’d do tonight.

Dr. Steven Novella: Sure.

Alex Tsakiris: So let me tee that up a little bit. As I just mentioned, the last episode of Skeptiko we talked a lot about near-death experience and actually, we have been for quite a few episodes now, trying to interview as many skeptical researchers, as well as proponents, as we can possibly reach out to.

The two things that I focused on in the last show were 1) your claim that there’s a lot of evidence that’s triangulating on the idea that there’s a conventional explanation for near-death experience and that explanation’s probably, most likely centered around the idea that these folks are hypoxic. They’re losing oxygen to the brain and that’s what’s causing this phenomena. So that’s point one.

Dr. Steven Novella: Can I clarify that a little bit? I think that we need to take a hierarchical approach to explanations. What I think, and I believe what I said is that the evidence is triangulating on the notion that it’s a brain phenomenon. Now, the deeper question of what exactly is going on in the brain to cause it, I think we don’t know that the answer to that is.

There are lots of clues; there are lots of possibilities, hypoxia being only one of those. I don’t think we can conclude at this point in time that hypoxia is what’s causing the near-death experience. I think it’s a very viable explanation. So I just wanted to back up on that. My point is that the evidence is clearly pointing to it being a brain phenomenon of some sort.

Alex Tsakiris: Okay, fair enough. Now, you did say that the near-death experiences are remarkably similar to what happens to the brain when it’s deprived of oxygen. So I do think you said both. You didn’t say it was absolutely, positively the only explanation. But that’s what I picked up on; that’s, I guess, what I was responding to.

Dr. Steven Novella: That’s fine. That was a brief discussion on our show about it. I think we can go into a little bit more detail here. I think that also for further context, it has to be noted that the consensus also seems to be moving in the direction, among neuroscientists who are looking at this issue, that near-death experience or NDE is not one phenomenon, either.

It’s descriptively very broad and it may, in fact, have as many different causes as there are types of experiences that people describe, that are being lumped into this sort of broad category of experiences we’re calling near-death experiences.

Alex Tsakiris: And there’s a jumping-off point right there. I don’t see where in the literature you can really point to, particularly among the near-death experience researchers, where there is this broad collection of different symptoms that are being lumped together or experiences that are being lumped together. If anything, it seems like they’re honing in more and more with the Grayson Scale being adopted more and more. We’re going to talk in a minute about the [inaudible] 0:03:53 CO2 study using the…

Dr. Steven Novella: Yeah.

Alex Tsakiris: …and the same with Kevin Nelson at the University of Kentucky using these same criteria, the same scale, to evaluate near-death experiences. So where are you coming from when you mention that there’s these kind of constellation of different things that are being broadly categorized as near-death experiences?

Dr. Steven Novella: Well, first of all, if you think about the core experience, the things that people are calling the core NDE experiences, there’s no single feature that’s experienced by everyone who meets criteria for having an NDE. Now these criteria are purely descriptive. It’s basically people interviewing those who have had near-death experiences describing and recording what they report and then just finding the commonalities among those reports and saying, “All right, that’s the core experience.”

But if you look at, for example, in Ring’s published data, if you look at each of the main features; separation from the physical body reported 37% of the time; entering a region of darkness again in the minority of times; seeing a brilliant light 16% of his patients; going through a tunnel or entering another realm was around 10%. Those are the core experiences and we’re getting 37%, 10%. The peace and well-being was reported 60% of the time. That’s the highest number. So that’s hugely variable.

In addition, there are different situations in which these occur. Basically the studies will focus on different patient populations, so of course if you’re looking at cardiac arrest survivors that are going to be homogenous because that’s the criteria that you’re looking at. But these same elements are also reported during anesthesia; during situations where people are hypoxic, like pilots who have become hypoxic have described elements of these near-death experiences…

Alex Tsakiris: Hold on. Let me jump in on that one. Again, I don’t think that’s what the data really says, at least my read of it, Steve. When you talk about hypoxia, the symptoms of hypoxia — both the subjectively reported symptoms by the people who have had that experience and the objective doctors saying that’s what they observed — to me seem to be exactly the opposite of what near-death experience researchers are saying patients are reporting back. The classic signs of hypoxia: inattentiveness, poor judgment, confusion, amnesia, and the list goes on, but they’re all of that kind of general…

Dr. Steven Novella: Yes, but you said it, Alex. Those are the signs of hypoxia, and a sign is something that you observe in somebody. A symptom is something that the person experiences themselves. Even when people are observed to look delirious with hypoxia, they may report that during that period of time they had the peace and well-being, a euphoric episode. They also at times will report a hyper-clarity or hyper-attentiveness that is described by NDE experiencers.

So the memory, the subjective experience of some people who are having clear-cut hypoxic episodes does overlap with NDEs. I think you were just absolutely wrong on that part. You’re confusing what people observe and what the people who experienced it remember and report as their subjective experience.

And again, keep in mind that you didn’t really address my original point where the core experiences are occurring between 10% and 60% of the time. This is a hugely variable experience that we’re talking about. I don’t think that everyone who reports an NDE is having hypoxia; I think probably just a subset are. We still need to sort out – and this is where the literature is very vague on this – we still need to sort out which features are more likely to be present in which kinds of situations. I think that there has yet to be consensus on the data on that.

Alex Tsakiris: There are a lot of different strings we can pull at here, but let’s pull at one because I think you misinterpreted what I was saying. Actually, if you look at some of the reports, particularly with pilots, as you mentioned, the subjective symptoms of hypoxia – and I’m reading right off of one and I’ll post for everyone the report that this came from – but here are the subjective experiences that the pilots reported:

These are not the symptoms of near-death experience, which are reported in mine are: vividness, increased sense of awareness, increased memory, “realer than real” experience.

These two don’t really match up, and I think to suggest that they do, you’ve really got to make a lot of leaps there.

Dr. Steven Novella: First of all, I’m not saying that pilots who are experiencing hypoxia are having a near-death experience. That’s not what I’m saying at all. Because the experience that they’re having is nowhere near what is happening to somebody who is having a cardiac arrest, for example, and needs to have resuscitation. So we wouldn’t expect the experiences to be the same. I’m saying that there are some elements of overlap. Like you specifically mentioned euphoria and tunnel vision.

But also, what you’re reading is not the full description of the kinds of different experiences that have been reported. Pilots have reported this sort of hyper-vividness and clarity, as well as hallucinations during the episodes of hypoxia. Again, I’m not saying it’s an NDE; I’m just saying there are elements of it. Most of the other situations in which we say, “Ah, here’s something that’s happening that overlaps with some of the elements of an NDE.”

It’s not a full-blown NDE, so for example, if you under ketamine, which is a drug, that can produce similar kinds of out-of-body experiences and euphoria that overlaps with an NDE. We can pretty much produce out-of-body experiences at will these days by stimulating the right part of the brain.

And it’s the exact kind of out-of-body experience that’s reported by those who have a near-death experience where they’re floating above their body. They’re looking down upon their body and the scene. That’s been reported during seizures; it’s been reported during non-dominant temporal lobe stimulations, specifically the angular gyrus during epilepsy surgery, for example. So to me…

Alex Tsakiris: That’s just not – I just have to…

Dr. Steven Novella: It’s not an NDE. Again, it’s not an NDE. But it’s an element…

Alex Tsakiris: I’m not saying it’s not an NDE…

Dr. Steven Novella: …it’s an out-of-body experience, which is one of the things on the list of symptoms that sometimes occur in some people with NDEs.

Alex Tsakiris: I’ll do a full follow-up on that, but I was just reading an article published in The Journal of Near-Death Studies, I think it is, that directly refutes what you’re saying about the out-of-body experience during seizure and the out-of-body experience by temporal lobe stimulation as being dramatically different than the out-of-body experience that’s reported in a near-death experience.

The authors of the paper went to great lengths to point out – I think you’re referring to an article that appeared in Nature Magazine in 2002 where it was first reported of the temporal lobe stimulation creating the out-of-body experience. And there’s significant, major differences. I think this is a very useful…

Dr. Steven Novella: Like what? What difference? People would say, “I’m floating outside my body, hovering above my body, near the ceiling out of my body…”

Dr. Steven Novella: Well, Alex, I had a patient who told me that directly, that he had a seizure and during his seizure he had temporal lobe epilepsy, and that’s exactly what he described. And I’m not talking about a paper. This has been described over and over again in multiple scenarios, seizures and epilepsy surgery only being one. We can produce it now with trans-cranial magnetic stimulation. I think you’re looking at a very tiny…

Alex Tsakiris: Are you talking about Persinger?

Dr. Steven Novella: Well, that was the original description from years ago, but again, there’s much more recent data looking at trans-cranial magnetic stimulation, in which we could much more reliably focus on different parts of the brain and either increase or decrease cortical activity. So this is becoming much more reproducible. I think you can’t just look at the NDE literature and get a feel for what we know neuroscientifically about how the brain works.

Most of the research that I think is relevant is just understanding how the brain functions. It’s looking at the neuroscience of what happens when we stimulate or turn off different nodules in the brain and what happens. It’s very clear now, very well established, that our sense of being inside of our bodies is something that is actively produced by different parts of the brain. And when you interfere with those parts of the brain, it gives you a feeling of being outside of your body, having an out-of-body experience. So…

Alex Tsakiris: I hear you.

Dr. Steven Novella: That’s well-established.

Alex Tsakiris: I’d love for you to provide me with references to where you think that best research is, because if it’s Blanke or Olaf, I mean we’ve looked at those, and again, what they really say is exactly what you said. That when we interfere with the brain’s understanding of its sense of self, we can create some of the symptoms of the out-of-body experience, but that it’s substantially different in many respects to what we’re seeing…

Dr. Steven Novella: Like what?

Alex Tsakiris: Particularly the floating outside and being able to see the entire view of what’s going on versus the sensation, the feeling of being outside and being able to observe and take in information and see and hear things that are going on, both there and other places. But I think that’s great. I’m very open to hearing that and pursuing that. The format of Skeptiko is that we really dig into things in great depth. I’ll drill into that as far as need be and try and contact those researchers and have them come on.

The last guy we had speak specifically to this topic that you’re talking about was Dr. Peter Fenwick. He’s one of the most highly regarded neuropsychiatrists in the UK and in the world. He appeared to me, Steve, to be extremely well-versed in the out-of-body experience, literature both from a neuroscience standpoint and from an NDE standpoint. He felt quite confident in saying that there were substantial differences.

And then we can get back to this other point, too, that I think if you’re trying to make the connection between hypoxia and near-death experience, great. Love to see folks who have done it, but I’m a little bit resistant to jumping on this kind of casual, hey, doesn’t euphoria sound like lucid experience in some way? I think what really needs to be done is some real hard-nosed breaking apart of what people are really experiencing and matching them up.

That’s why we had on Dr. Jeff Long, who did a 150 question survey where he extensively went through asking multiple questions multiple different ways to try and dig into what people were really saying when they said they had a real experience. Or when they said that 96% of what they encountered was accurate and realistic, so i.e., not hallucinatory.

One of the things that you just mentioned before, I think is another trap that NDE –I don’t want to say skeptics but people who are not sold on the NDE as being indicative of consciousness separate from the brain, but they immediately lump these experiences into being hallucinatory. What the data is coming back from the NDE researchers is just the opposite; that these folks are reporting that these are very non-hallucinatory experiences, in terms of how they’re experiencing it. People can tell the difference, right? We know what dream-like means because we all dream. People who have hallucinations can differentiate between saying, “That’s a hallucination. My car turned into a lion. That was a hallucination.”

Dr. Steven Novella: Well, that’s actually only true part of the time. There are certain types of hallucinations that people know they’re not real and there are certain ones that they don’t know are not real. In fact, that’s a diagnostic criteria that we use in order to distinguish different types of hallucinations. So it really depends.

And again, I think what you’re doing, Alex, is trying to dismiss certain neurophysiological explanations because they don’t meet all of the features of an NDE, but you really can’t dismiss them on those grounds.

Again, I think if you look at this as there are probably multiple different things that all produce elements of an NDE. There are multiple like pathways that can be taken to get there. Nothing is going to be the exact same as, for example, having a cardiac arrest and undergoing CPR, so I wouldn’t expect anything else to produce the entire experience that’s really similar to an NDE. But I think it’s relevant that there is a part of the brain that when you turn it off, it makes people feel like they’re floating outside their body, and that is what people who have a NDE experience and report.

I think it’s very interesting that there’s a part of the brain that can also give you euphoric experiences, or that we know that neurochemically, for example, this is another sort of physiological hypothesis that during the extreme stress of either hypoxia or having a cardiac arrest, that endorphins can be released as a neuro-protective chemical, and that endorphins, when they bind to receptors, can produce euphoria and the kind of everything is pleasant experience that some people report with a NDE.

And in fact, it’s been reported that in patients who have had naloxone, which blocks those receptors, that they have the more negative NDE experience. Why would a drug change the way someone experiences their near-death experience unless it were a brain phenomenon?

Dr. Steven Novella: I will send you a good overview that gives all of these references that I’m going to be talking about tonight.

Alex Tsakiris: Just let me interject before I lose my train of thought, because I thought it was interesting what you were saying about me dismissing the neurological basis for this. It seems to me like I could take the path, the logic stream that you were going there, and kind of turn it around.

Why would we expect someone who is under general anesthesia for whatever operation, and someone who suffers sudden cardiac arrest and someone who’s drowning, all very different from a physiological standpoint, from a neurological standpoint. Why would we expect, as we do find, that their experiences are very, very similar in terms of near-death experiences? And again…

Dr. Steven Novella: But there’s an easy explanation for that. It’s because the symptoms of neurological phenomenon are not determined by the cause. It’s determined by what parts of the brain are not working. And that’s it. So I can damage a certain part of your brain in a hundred different ways. It would all produce the same symptoms because those symptoms are determined solely by which brain cells are not working. Not by what the insult was.

Alex Tsakiris: But hold on. I mean the real point on that – I hear where you’re going, but let me fine tune it so that – that’s a fine answer but apply it to this. When someone’s drowning, the breakdown of the brain and the brain cells is gradual, slow, we know that, right? Cardiac arrest, we know it’s much more sudden. Anesthesia, we have no way of explaining why there would be any conscious experience. Yet the experience that’s reported across all of these is the same.

Dr. Steven Novella: Well again, I disagree that they’re the same in that you’re still talking about a very broad experience with lots of features that are no single feature is present every time. A lot of the core features are present even in a minority of cases so I don’t think that we’re dealing with…

Alex Tsakiris: That’s the Kenneth Ring data that you pulled, which is fine. That’s one way to slice the data…

Dr. Steven Novella: But even if that’s one data, but even if you just look at anyone’s description of it, there’s no description…

Alex Tsakiris: It doesn’t have to be 100%. You’re saying that the percentages are very low, which I admit on one thing. If they’re 16%, 20%, but when realer than real experiences 76%, when realistic data reported is in the high nineties, when meeting only deceased relatives is in the high nineties, it really puts a completely different spin on this idea that we don’t have a lot to grab onto, because we do.

Dr. Steven Novella: I think that what this means is it’s reasonable to hypothesize that there are different kinds of experiences here that have neurological overlap. Again, as a neurologist, this kind of explanation makes perfect sense to me, because we see this in all areas of neurology where we have different kinds of disorders, maybe with completely different causes that have similar symptoms. There are final common pathways of neurology, of how things operate. And you can interfere with some function in multiple ways and it will cause a lot of overlap of symptoms. So I think that is the way to approach this.

Alex Tsakiris: I hear what you’re saying in a way, but it seems to be contradictory to what I’m saying. If somebody has a cardiac arrest and we know that their brain is going to shut down within 10 to 15 seconds of that, why would we expect…

Dr. Steven Novella: It could be a little longer than that.

Alex Tsakiris: Okay. Well, why would be expect that experience to be similar to someone who is in and out of consciousness while they’re drowning? Or why would we expect that experience to be the same as someone who’s under general anesthesia, who even if you speculate and say there’s anesthesia awareness there, there’s all sorts of symptoms that are associated with anesthesia awareness that we don’t see. So for you to kind of funnel that all into this common pathway of what’s going on neurologically, to me, I don’t see how you get there.

Dr. Steven Novella: I think it makes perfect sense, but I also think that you’re mixing two other kinds – you’re at least assuming that two potentially different kinds of phenomena are one thing. So just to back up a little bit, there are three kinds of broad categories of explanations for NDEs. I don’t have any bias going into this. I, just like anybody else, just want to understand this as best as I can. The three basic kinds of explanations are 1) it’s spiritual, that it represents the fact that the mind can exist separate from the brain; 2) is that it’s psychological…

Alex Tsakiris: Hold on, but that first, that isn’t in and of itself spiritual, right? A separate mind from a brain isn’t necessarily spiritual, right? It’s just…

Dr. Steven Novella: Well, it’s non-materialistic. There is no materialistic…

Alex Tsakiris: It’s dualistic.

Dr. Steven Novella: Yeah, it’s dualist. I don’t want to get caught up on the word “spiritual,” but you know what I’m getting at. It’s a dualist and mind separate from body explanation. 2) The second one is that it’s a psychological experience of some sort; and 3) it’s organic, it’s neurophysiological. I think that the evidence and some of the best explanatory models that people are putting forward are blending the second two, the psychological and the organic, the neuroscientific.

I think there are some psychological explanations that have been correctly dispensed with. I don’t think this is a triggered birth memory. I think that was kind of a silly idea. So there are some that I think have nothing to do with NDEs. But then there are others, and – again, I think you got this wrong on the previous show when you were talking about this – there are others that are culturally specific and that appear to be psychological.

So I think what we’re seeing is that there’s a core experience. There are six or seven or so very, very common although not universal elements to the NDE that are considered the core experiences. I think that’s primarily organic. It’s the kinds of things that can happen to the brain under various kinds of stress and the reason why those are cross-cultural is because it’s a brain phenomenon, not a cultural phenomena.

Alex Tsakiris: Like what are those? What are you talking about when you mention – because I think the data does say exactly the opposite of that. What are the cross-cultural aspects that have been reported that you think you see directly tie back to physiological brain function?

Dr. Steven Novella: Again, I want to complete my point, but just to go over that again, I think that things like sometimes feeling euphoria, sometimes feeling an out-of-body experience, the tunnel vision, the bright light, I think those are probably more physiological, a brain phenomenon, and therefore it doesn’t matter what culture you’re from. Your brain is shutting down in a certain way. That’s the kind of experience you’re going to have. So that is occurring during some kind of physiological stress, while it’s at the very beginning of a cardiac arrest before the brain totally shuts down, or during a drowning episode, or maybe during anesthesia, or some other kind of stress.

Then patients are unconscious for a while. After a severe episode like a cardiac arrest, patients will probably be unconscious for a day or two. Then they’re slowly waking up. They remember this really unique experience that they had, that they have no way of dealing with in their ordinary experiences of life, because they were literally having an experience with a different subset of their brain. They’re trying to make sense of it. They’re trying to remember exactly what it was that they experienced; meanwhile, they’re not really fully out of their delirium or whatever they’re passing through on the way to fully waking up.

And then I think that’s where a lot of the cultural elements come into play. When they’re trying to process this memory and this experience, they’re trying to remember it and this is probably a life-altering event for them, so their emotions are running extremely high. When you look at those elements, like meeting deceased people, where it’s more of a cultural element, then you get higher percentages within a culture, but it also differs when you look at different cultures.

Alex Tsakiris: That’s not true, Steve.

Dr. Steven Novella: It is absolutely true. I’m sure the literature is probably mixed on this, but there absolutely are studies that show that there are cultural differences in those kinds of experiences.

Alex Tsakiris: There are some cultural differences like you pointed out in terms of seeing religious figures associated with your background. There are also cultural differences in the language they use. Tunnels for some and holes for others. But we can focus on those languages, but they’re primarily in a language specific to these religious figures.

What contradicts what you’re saying — I don’t know how much you’ve really immersed yourself in the near-death experience research, Bruce Grayson, Jeff Long, who we’ve had on the show. And Jeff Long, who we’ve had on a couple of times, he’s compiled the largest database of near-death experiences and did it in a very scientific way. He’s a medical doctor; he knows what he’s doing. It just completely contradicts what you’re saying.

And in the cross-cultural part, for example, the deceased relatives, one thing that jumps out at you there is these folks, when they see relatives, they only see deceased relatives, 92%, cross-culture. That doesn’t fit in your model. There’s no reason why someone from Singapore would only see deceased relatives versus – these are cross-cultural kinds of things that shouldn’t really be there. The life revealed…

Dr. Steven Novella: I don’t think you can say that. First of all, we’re jumping onto different points, but the life review is actually – that’s a brain phenomenon, so I wouldn’t – that can be induced, again, by physiological stress to the brain.

Alex Tsakiris: Another one is the choice – go ahead, I’m sorry.

Dr. Steven Novella: But the thing is, while there are the things that are different among cultures like religious belief and the importance of certain things like food or whatever, if you look at those kinds of elements that are very specific to one culture in one way or another, those things differ in how patients are remembering and making sense of their near-death experience. Those things that are universal, there are some things which are universal across-culturally even though they may not be purely neurological, you’re going to see 90% of the time. Like people are trying to make sense of a near-death experience, sure they’re going to see people that they know are dead. Why wouldn’t that be cross-cultural?

Alex Tsakiris: Why would it be?

Dr. Steven Novella: That wouldn’t be different.

Alex Tsakiris: You know, you can fit it into any box but there’s…

Dr. Steven Novella: But death is death. When people think of death, you think in Asia they think that people are alive or in the afterlife? I mean, that kind of thing is pretty universal.

Alex Tsakiris: When you dream, you don’t only see deceased people in your dream…

Dr. Steven Novella: But I don’t think – first of all, I don’t think near-death experiences have anything to do with dreams. I don’t think it’s a dream-like experience. That’s a specific neurological phenomenon that is not going on with NDE.

Alex Tsakiris: You believe Kevin Nelson’s work, University of Kentucky, is completely on the other side of that REM intrusion thing that hit the media and was really big about a year ago?

Dr. Steven Novella: I’m not convinced by the REM intrusion hypothesis. I think it’s an interesting idea. I think we would need to see a lot more specific data in that direction to make me think that that’s happening. But even if it was REM intrusion, it still is not a dream state. REM sleep or REM dreaming is different. It’s a very specific neurological state and that is certainly not the state of people who are having a near-death experience.

That doesn’t mean that there can’t be elements of that, of again, of neurological function that’s involved in dreaming that then can get involved in the period of time in which people are forming memories that they then later report as a near-death experience. So I don’t think we can rule that out. My point is that we have to be clear on the fact that dreaming is not a pathological state. It is a normal state of our brain. That doesn’t mean that pathological state can’t somehow involve neurological structures that are also involved with REM or with dreaming.

Alex Tsakiris: Okay. You’re going to give me so much material here to sort out and go follow up on, which is great. I love to do it and I appreciate it, I really do.

Dr. Steven Novella: You threw out a lot of references, let me just give you one reference. There’s an article by John Bellonti, where he specifically looked at a cross-cultural perspective of near-death experience, and he showed that as the cultural elements varied, so did the NDE and I can send you that reference.

Alex Tsakiris: Sure, and I’ll be happy to follow up on it and talk to as many people as I can and find out where that really shakes out.

I would have to back up, though, because one of the major points that you just made which I just don’t see any support of in the literature, is this idea that you have that these memories that are being formulated after the fact and are somehow being formed based on their psychological factors that drive them to do that.

The research that I mentioned and I spoke with her on our show here, is Dr. Penny Sartori, and that’s been corroborated by other researchers who have gone back and tried to match the resuscitation experience and what the experiencer remembers about the resuscitation experience and compared that to the group of cardiac arrest patients who didn’t have a near-death experience. And the results are dramatic. It’s dramatically more likely that they’re able to recount accurately their resuscitation experience if they had a NDE as opposed to if they didn’t.

The bottom line of that is that it directly contradicts this idea that you have that they’re somehow formulating all these memories after the fact.

Dr. Steven Novella: There’s the rub, right? So now we get to the real thing that can distinguish between a mind-separate-from-body experience versus a purely neurological, psychological experience, a brain experience. During the period of time when someone is undergoing CPR, after the first 30 to 60 seconds or so, it’s fairly quick, but it could be up to a minute or so, depending on exactly how catastrophic the cardiac arrest is. They’re not getting enough blood supply to the brain or they’re not getting any blood supply. The brain starts to shut down.

After about a minute, the EEG goes flat-line, right? And it’s going to be flat-line now for hours. And they’ll slowly come back if they’re successfully resuscitated. During that time when the EEG is flat-lined, I think everyone would agree that the brain is not going to be making memories, right? In the ordinary way that it does with brain function.

So therefore, if we could really demonstrate that patients were having experiences that they had to be having during that period of time, that would certainly call into question our current models of neuroscience and the whole mind-brain connection. I agree with that. But I and many others don’t think that there is any evidence that definitively rules out that those experiences are forming at other times. I don’t think we can check that box and say that we’ve demonstrated clearly that the experiences are happening during that time.

Alex Tsakiris: Hold on, hold on. Let me stop you right there. I hope I didn’t cut you off too soon to make that point, but I really want to get in here.

Dr. Steven Novella: Go ahead.

Alex Tsakiris: That’s the rub, to use your term.

Dr. Steven Novella: Yes, yes.

Alex Tsakiris: But that’s the rub the other way. You talked about triangulating data. The data is triangulating towards that point. So Penny Sartori’s work is triangulating towards those experiences happening during a flat EEG. Dr. Jeff Long’s research is triangulating towards those experiences, those memories being formed during a flat EEG. Steve, even the CO2 study that you mentioned as kind of offering support for your view, if you read in the conclusion, and I’m reading from it here, it says:

“Our findings concerning the association between initial PET CO2 and the occurrence of NDEs therefore supports the hypotheses that NDEs occur during cardiac arrest.”

So really, the data is triangulating towards that point and I can say it’s…

Dr. Steven Novella: I disagree. I think that first of all there isn’t consensus on that by any means; that different people interpret that data differently, different researchers looking at NDEs and different scientists. Have you interviewed Susan Blackmore?

Alex Tsakiris: Yeah, I read Susan Blackmore what, 20 years ago, and I don’t think she stands up very well, but what we’re talking about it is the CO2 study. I have to get back to that, too.

Dr. Steven Novella: Let’s get back to the CO2 study. By the way, you got that wrong about the CO2 study last week when you criticized my interpretation of it.

Alex Tsakiris: I don’t think I did. You can tell me where I’m wrong. But right there, it’s interesting that you say there’s not consensus and there’s disagreement. You’re disagreeing then with the authors of the study who say that it support…

Dr. Steven Novella: Yeah.

Alex Tsakiris: Okay.

Dr. Steven Novella: Absolutely. That was, in fact, my criticism of them, was that I think they’re leaping to that interpretation. But we can’t really say that. And they, in fact, if you read their full conclusion they say the other interpretation is that the high CO2 during the CPR could just be a marker of high CO2 at other times or other metabolic effects at other times. And that was my very point, which the authors of this paper agree with.

But to get back to that, from your discussion on the previous show, you said that I misinterpreted the timing of things in this study. But I think you misread the study about that, Alex, because what the study says, it was out of hospital cardiac arrests, right? But out of hospital CPR, resuscitation. I think you interpreted that as the resuscitation happening in the field or something like out of a medical setting.

But actually they were quite clear in their methods that the out of hospital CPR occurred in an emergency medical setting. It was just not one that was attached to the hospitals where they did the study. And the PCO2 was drawn during CPR. So I was absolutely right in my discussion of the study and you simply misread that.

Alex Tsakiris: The PET CO2 was, but the blood was drawn after they were resuscitated.

Dr. Steven Novella: Well, there was blood drawn during the resuscitation, there was blood drawn after the resuscitation, and the CO2 was elevated actually in both.

Alex Tsakiris: No, the CO2 was only elevated in after. The first ones were normal.

Dr. Steven Novella: I disagree with that.

Alex Tsakiris: Go check. Go check the work.

Dr. Steven Novella: So the scores on NDE scale were positively correlated with the PET and title CO2. And that was the one that was drawn during the CPR. And it was both. It says it was the PET CO2 and the partial pressure CO2. They both positively correlated with the risk of having a NDE. The serum potassium…

Alex Tsakiris: They may have correlated, right? They may have correlated versus the other patients, but the PET CO2s were at normal levels but relative to normal patients, normal walking people.

Dr. Steven Novella: But the point is the higher the CO2s, I’m not saying normal, abnormal, just the higher CO2s correlated with NDEs. That’s the point of their paper.

Alex Tsakiris: Right. And we also should say that statistically, really if they use – and Bruce Greyson pointed this out – using the normal means that we do, the results aren’t even statistically significant, so it’s very weak in terms of…

Dr. Steven Novella: No, the correlation with CO2 was statistically significant. It was .01 P-value for the initial CO2 and .041 for the after CO2.

Alex Tsakiris: Right, but as Dr. Greyson points out, when you’re doing multi-variable analysis – and you would know this much better than I, so I don’t want to get too far into that – the normal standards of significance that you would use are lower than .05.

Dr. Steven Novella: Oh, I agree. I don’t know if actually that’s a good point. I don’t know if they adjusted for multi-variable analysis, and if not, then again this is something else that I criticized the study about. It seems like there were anomaly-hunting a little bit.

So you can interpret the study in a few different ways. You could say so they were looking at a host of things; they found a few correlations; they might not really be meaningful. They could have just been anomaly-hunting. My other criticism was that even though they were drawing the CO2 during the CPR, and that’s the one that most highly correlated with NDE, that the…

Alex Tsakiris: I think the other one was…

Dr. Steven Novella: You don’t know when the experiences were happening. No, the higher statistical significance was with the initial CO2. I’ve got it right in front of me.

Alex Tsakiris: The PET CO2?

Dr. Steven Novella: Yes, yes. It was .01 versus .04 for the one that was later. So the point is they don’t know when the experiences of the NDE were happening because these people were interviewed several days later.

Alex Tsakiris: Right. But their conclusion is that it happened during the cardiac arrest. And there’s one other thing, as long as…

Dr. Steven Novella: But Alex, you can’t get away from this, Alex, because how do you make sense of that? Because why would CO2 have anything to do with if this a mind separate from brain phenomenon?

Alex Tsakiris: Look, I’m with you on that. I did a whole show on why the scientific media covered this study with 11 patients that has all these inconclusive correlation versus causation. Why they covered it in the way that they did? But moreover, and I have to throw you in the lot here, that as they did cover it, your conclusions directly contradict the conclusions that they drew, the authors of the study.

Dr. Steven Novella: I don’t have to listen to the authors. I’m looking at their data and coming to my own conclusion. I think…

Alex Tsakiris: But your own conclusion is the same as mine; it’s that the study isn’t important; it isn’t significant; it isn’t something we should look at. Particularly so it’s small study size. It’s not statistically that significant. There’s the correlation/causation thing, and there’s prior research as again, Bruce Greyson, who is the guy whose survey they used and translated into Slovenian for their thing. As he said, there are plenty of better studies that contradict this idea that there’s some connection between CO2 and NDEs. But I would have to add this one last thing, because I think it gets lost, and that’s that the conclusion that they draw at the end, and this is another quote from the study:

“It’s not thought possible to explain NDEs only in terms of physiological processes.”

So even these guys, when you talk about triangulating, they’re adding a brick to the other side of the wall, if you will, than the wall that you’re building.

Dr. Steven Novella: I don’t know how to make sense of this study. I agree, this is a small study. You can’t really make too much of any single study. This is only interesting in that it was prospective. There is some prior data to suggest that you can have some of the NDE elements with hypercarbia, with hypercapnia, with increased CO2, so this isn’t coming out of the blue.

There is prior literature with CO2 – not saying necessarily correlating with NDEs, just people who have high CO2 can get some experiences that overlap with NDE, so that’s why they would even look at that. But I didn’t make too much out of this study. I also don’t think that the authors’ conclusions are justified; and they even admit themselves that it could just be a marker for other things. It could be that the people who had the higher CO2 had physiologically…

Alex Tsakiris: Resuscitation.

Dr. Steven Novella: …yeah, whatever, better resuscitation, worse resuscitation, whatever. You can sort of make sense of it in any different way. It could be saying something that would affect the induction period, when the experience could have been happening or even the after-effects. So you can’t make that conclusion from this study, I don’t think. I think we’re actually on the same side here. Neither of us thinks this study is terribly important as far as NDE research; it’s just one study.

But also, I’m interested in just that notion that how could you use a physiological marker to argue that the experience is not physiological? I don’t understand that. I think there’s an inherent contradiction there, so I don’t think this study can possibly lend support to the mind separate from brain hypothesis because it’s contradicting it by its very premise that CO2 would have an effect.

Alex Tsakiris: I’m not sure that I totally agree with you there, but the one point I would draw out because it’s going to be interesting when we followup on the research that you provide is these guys were looking at near-death experience, at least. But so much of the research that I see referenced – when you’re going to talk about out-of-body experience and maybe you’re going to send me Persinger and Blanke and Olaf and the rest of these guys, hey that’s great.

But if they weren’t really looking at out-of-body experiences as they relate to near-death experiences, then we get into this other area that I guess I would accuse you of stepping into in this conversation a lot in terms of saying, “Hey, isn’t there some overlap there? Doesn’t that sound like some overlap euphoria? Couldn’t we interpret that as overlap?” versus you’ve got to go if you think that overlaps with the near-death experience, then you need to drill down and use the same methodology that the folks who’ve studied the near-death experience do? And you need to really drill into these experiences.

I guess I’ll come back to my question that I had for you. How much – and I don’t know the answer to this, Steve – but how much have you really looked into analyzing…

Dr. Steven Novella: Alex, I’ve read a lot of the – there’s actually not that much in terms of medical research. There’s what, hundreds of relevant studies. That’s the kind of thing you can kind of get a grasp on, and I’ve read a lot of the NDE research. Not all in the last week. I’ve read it over years. But…

Alex Tsakiris: So what do you think of Bruce Greyson’s research in general? What do you think of Jeff Long’s research in general?

Dr. Steven Novella: I think a lot of that research is descriptive. A lot of it is just describing what has happened, which is fine and that’s a good starting point. But I don’t think that what we have is anything – in getting back to that rub question about is the experience happening during the flat-line?

There actually was one study that never got completed because it was set up and then nobody actually had a NDE, where they hid a hidden object or message or something out of view from anybody in the ER. The only possible way you could see this is if you were floating up near the ceiling, right? You had to be near the ceiling and have that kind of perspective. And the question was if somebody were having a genuine out-of-body experience where their consciousness was out of their body and floating up near the ceiling, not just the subjective sense that that was happening, then they would be able to see what was there and report on it. And that would be objective evidence of a true consciousness outside of body experience.

Unfortunately, they never pulled the trigger on that study because while it was set up, nobody had a near-death experience, so they never actually carried it through. But I would like to see that kind of study…

Alex Tsakiris: That’s Sam Parnia and the whole Aware group and Peter Fenwick and they’re doing that again.

Dr. Steven Novella: Yeah, I’d like to see those results.

Alex Tsakiris: Hey, we all would. But from what I hear, their preliminary results, these things take years to publish, but Sam Parnia has publicly said that the initial results are very positive in establishing their hypothesis, which they’ve been on for years. So I think that the direction line here is heading in that direction.

Dr. Steven Novella: Well, we need to see published research.

Alex Tsakiris: We do, but we have published research when we talk about Penny Sartori and that’s published research. We have published research with Dr. Jeff Long. He looked at 23 patients who were under general anesthesia. Again, there’s no good, conventional explanation why someone under general anesthesia would have these experiences.

In my report last week I think I told you the account of when – now that’s the account – but that’s backed up by a 150 question survey, cross-correlated and done in a way to prevent misreporting of information. So there’s some good solid data to support this unexplainable situation of people having these memories, these experiences, during general anesthesia.

Dr. Steven Novella: I don’t think that’s unexplainable at all. Any anesthesiologist will tell you, Alex. Let me explain it. You made a claim it was unexplainable. That patients can wake up during anesthesia. That happens. And they’re paralyzed and they are on medications to block any pain and during that – so imagine waking up and being completely numb to any sensations and being paralyzed and that can absolutely produce an out-of-body experience. And yet there are other senses – they could hear, for example, and they will visualize what the scene that they’re imagining taking place in the operating room. That is a perfectly plausible explanation for those cases. So…

Alex Tsakiris: Not really. Now we had…

Dr. Steven Novella: Oh, absolutely.

Alex Tsakiris: Not really. We had Dr. G.M. Woerlee on. I’m sure you know who he is.

Dr. Steven Novella: Yeah.

Alex Tsakiris: He’s a very highly, well-credentialed hard-working anesthesiologist in the Netherlands. We had him on twice. And we had Jeff Long on, as well. It doesn’t hold up. This idea of anesthesia awareness, first of all that’s rare. I mean, that’s one in a thousand, one in ten thousand, if you look at the research. The other thing is it has all sort of symptoms associated with it that don’t show up in any of these cases. But just the pure odds that out of these 2,000 or so people in this sample, that 23 of them who were under general anesthesia, that they would all have anesthesia awareness. The odds are astronomically high.

Dr. Steven Novella: First of all, I’m not saying that they all had anesthesia awareness. Again, you keep resorting to this fallacy that there’s one explanation for everything. I don’t think that that’s the case. But I was talking about the unexplainable case that you specifically presented on the last episode. That one certainly sounds a lot like an anesthesia awareness case, to me. There may be other things going on in some of those cases as well.

Alex Tsakiris: Let me just ask a question here. I’ll make it really quick. What would it be if it’s not anesthesia awareness? You’re under anesthesia. If you have any awareness, it’s anesthesia awareness.

Dr. Steven Novella: Well, I haven’t read every single one of those reports so I don’t know if they all fit narrowly into that description or not, or if it could be contaminated by memories that again, occurred after the operation, etc. But if it is corroborated by them having to have awareness during the surgery because they reported details that they could only know if they were aware of what was happening in the operating room, those cases can be explained by anesthesia awareness. Absolutely.

Alex Tsakiris: Which you’d acknowledge is extremely rare.

Dr. Steven Novella: I don’t know off the top of my head what the percentage is, but you know what? Even if it’s one in a thousand, that’s a lot of surgery. That’s a lot of cases that would be out there.

Alex Tsakiris: It’s more like one in ten thousand. And the population we’re really talking about here in terms of cardiac arrest patients, at least in Jeff Long’s study, you’re talking about a population of 2,000. So to have 23…

Dr. Steven Novella: Maybe it’s more common than we think…

Alex Tsakiris: But that’s not what the data says. A lot of people have been to a lot of anesthesiologists, researchers who have been looking at anesthesia awareness because it’s a huge problem, right? You don’t want to be coming aware during anesthesia. So we have a lot of good data on the fact that it is quite rare.

Dr. Steven Novella: The point is it depends on how you define what anesthesia awareness is. So in these “NDE studies” you go back and you ask people what kind of experiences they had, right? If they’re defining the experience differently than how you’re defining anesthesia awareness, you’re going to come up using different criteria. You’re going to come up with different statistics. But we don’t know a priori that these are, in fact, different experiences, right?

So in fact, I know this is circular, but if you count those as anesthesia awareness, then of course it’s much more common. The point is we don’t know. Again, it’s purely descriptive. And that is an inherent weakness in a lot of this data. And this is why I don’t pretend that we know exactly what the near-death experience is. I think that the fact that all of the elements can be reproduced by brain phenomenon strongly argues that in the final analysis it’s going to be explained as a brain phenomenon.

I think that there’s no smoking gun evidence that it can’t be a brain phenomenon. As much as you want there to be, it just is not out there and there’s no consensus that there is. There are viable explanations for everything that can explain it without rejecting the brain hypothesis. But the weakness of it and the reason why I think that we’re making a lot of inferences and nibbling around the edges is because most of the data is retrospective and observational descriptive data.

You really can’t do controlled experiments on this. You can’t give people hypoxia or heart attacks to see what happens and control the variable. So this is going to take a long time to sort this out because we’re trying to use a lot of inference and I think the state of the research at this point in time is such that we don’t have a definitive answer as to what’s causing near-death experiences. I think it’s a very complex set of experiences; that it’s probably going to have likewise a complex set of explanations. I think we’re starting to get a handle on that, but we’re not there yet.

But I do think that the notion that it’s caused by brain function is a completely viable explanation. We can’t reject it with existing data, and I think there’s a lot of reason to infer that it is. Let me give you one that I was trying to bring up before, and that is if patients who are getting a lot of drugs during the cardiac arrest, they tend to have fewer NDEs and the NDEs are muted. The experiences have a lower chance of being vivid and they have a lower chance of having a near-death experience. Now, if it weren’t a brain experience, why would drugs have any effect on it whatsoever? That really only makes sense if the NDE is a brain experience.

Alex Tsakiris: Steve. Okay, so let’s look at that study. Send me that study. We’ll pull it apart. We’ll get the authors. We’ll get the other folks who don’t see it that same way. But I’ve got to take that and turn it around, Steve. That’s descriptive. This whole thing of descriptive kind of sets me on tilt a little bit because everything we’re talking about here in terms of anesthesia awareness, all that…

Alex Tsakiris: No, no, that isn’t a good point because we cannot – to suggest that we cannot probe these topics because the data that we’re going to get back by doing so is going to be descriptive and not experimental, and therefore we can’t go there, I just don’t think…

Dr. Steven Novella: I didn’t say that. I did not say that.

Alex Tsakiris: Hold on. Hold on. I think you said…

Dr. Steven Novella: I just said it’s a lot harder. I just said it’s a lot harder.

Alex Tsakiris: We’ll go back and play it and everyone can interpret it the way that they want in terms of what you said and what I said. But what I’d say about your last point, Steve, is take that – take your argument now and allow me to use that argument as it applies to the anesthesia, the 23 anesthesia patients in Jeff Long’s study that we just talked about, right?

Why would they not have the normal symptoms that we associate with anesthesia? Grogginess, amnesia, all these other things? So you just made a point of hey, these people in this study that you’re referring to, they were under a certain drug that you would – why would that drug affect their experience? Well, why would the drugs from anesthesia not affect the experience of these folks?

Dr. Steven Novella: Alex. But you’re assuming that drugs affect people all in an identical way, and that’s a naïve assumption. Neurologists and physicians understand that there’s a huge spectrum of how people respond to medications. People have different brains. Yes, they’re remarkably similar, but there’s also interesting differences. People have different…

Alex Tsakiris: But if you understand my point, I’m saying that they weren’t affected. So if they…

Dr. Steven Novella: How could you say they’re not affected? Maybe the effect was that it was impairing some parts of their brains significantly and that gave them the – more than other parts of the brain…

Alex Tsakiris: Let me answer your other – why am I saying that? I’m saying that because that is exactly what was reported in Dr. Long’s study, is that those patients who were under anesthesia were not different significantly in any respect from any of the other near-death experiencers he studied with the exception of one, a slightly higher percentage of them had the tunnel experience. So that’s what I’m saying, is that your point is that you would expect the differences and you don’t see them.

Dr. Steven Novella: Not necessarily. As I said, there could be multiple pathways that you can get to the same brain experience. If the NDE is largely due to some module in the brain being shut off while other modules are functioning, there could be ten ways that you could make that happen. Anesthesia, hypoxia, hypercapnia, whatever. Maybe even just extreme emotional distress. Seizures. Other medications.

But it would still produce the exact same experience or at least a similar core experience because it’s the same net result on the brain; that this module shutting down resulting in a different subset of different parts of the brain functioning, which therefore authors the way the brain constructs reality. And that produces a NDE.

It’s an altered construction of how we construct reality, put ourselves into that reality, how we relate to that reality. In fact, it may seem paradoxical, but if you impair reality testing, then that could give you a sense of hyper-reality, because now you’re not filtering it all. It all seems hyper-real to you and that can occur by impairing part of the brain. So I think that the similarities can make absolute sense, even under totally different situations, as long as it can plausibly result in altered brain function.

Alex Tsakiris: Well, I have to say that you’ve given us, in this hour talk we’ve had, kind of more grist for the mill than I could have possibly hoped for.

Dr. Steven Novella: [laughs] Great.

Alex Tsakiris: So there are a lot of strings to pull and I really do appreciate it. I think it’s great and you certainly haven’t disappointed me or I’m sure, any of the Skeptiko guests, in terms of 1) your willingness to engage directly on these topics and just provide a lot of insight in a very articulate way of expressing the other side, the materialistic explanation of what’s going on. And for that, I have to really thank you.

Dr. Steven Novella: It was a lot of fun, Alex. Anytime.

Alex Tsakiris: It’s amazing how much feedback I get from folks when I dare challenge any of these points, particularly with you, Steve. You’re just so loved by your group out there, I think they always feel a need to rally around and defend you. What I found myself saying over and over in the forums was, “I don’t think you guys are giving Steve enough credit.”

In the conversations I’ve had with you in the past, I got the sense that this kind of give-and-take is something that you’re pretty familiar with and really not afraid of. So do you want to give any kind of insight into the give-and-take that needs to go on to really get to the bottom of this? And how we can really engage in this dialogue about these topics and about the research?

Dr. Steven Novella: This is how science functions, right? It’s very confrontational in many ways. People take their positions and then they will defend them, hopefully with logic and evidence. And then you sort it out. It’s a meat-grinder, and that’s a good thing. It doesn’t have to be even polite, although it often is, but it often isn’t. If you’ve ever been in a scientific meeting, you hear respected, even elderly, very reserved scientists, get very passionate and start beating each other up over some really minor technical point. But that’s great. That’s what science is all about.

I just think we need to keep it obviously intellectually honest. We want to keep focused on the science and the evidence and logic, and honestly try to resolve these factual differences. It’s good that you and I are talking about the research; we’re talking about what’s published; how to interpret it; what different people are saying. I know there’s a range of opinion on this. I know that there are dedicated NDE researchers who think that it’s a dualist explanation. I’ve read them; I know what they say.

But there are also people on the other side who have, in my opinion, very cogent arguments against that. There isn’t a consensus. I’m obviously on one side. I’m very compelled by the neuroscientific arguments because that’s in my specialty and I can very clearly relate to them. So I think this is all good. As long as we’re not making it personal and we’re focusing on logic and evidence, then it’s very useful.

Alex Tsakiris: I couldn’t agree more. Well, Steve, thanks again for joining me and we’ll be sure to followup, if nothing else by email. Maybe we can steal a little bit of your time; I know you’re a very busy guy, but maybe we can drop you an email here and there and get your ideas on some of the things we might find out.